Several different solutions exist in order to provide a suitable voltage to an electrical circuit, both as supply voltage and as voltage input to the circuit. Often a Direct Current/Direct Current (DC/DC) converter is used to convert a voltage from a fixed level to another level, for example step up or step down. Similarly Alternating Current/Direct Current (AC/DC) converters are used to convert an AC voltage to DC voltage at a certain level.
It is known to use an electrical transmission line for DC/DC voltage conversion in a switching manner using short pulses traveling in the transmission line and synchronizing switches to perform the DC/DC voltage conversion. This is known for example through WO2008/051119.
“Multi-resonant passive components for power conversion,” by J. Phinney, Ph.D. Thesis, Dept. of Electrical Engineering and Comp. Science, Massachusetts Institute of Technology, Laboratory for Electromagnetic and Electronic Systems, 2005 describes a push-pull converter, in which two switches are used to generate an AC square-wave output on the transformer secondary. By replacing the center-tapped transformer with a multi-resonant transformer having the appropriate dynamics it allows one switch and a primary winding to be eliminated. The multi-resonant transformer may be either single resonance links or an entire transmission line. However, the switch elimination example is only applicable to a transformer isolated circuit and can not be used for switch elimination in fundamental non-isolated buck, boost or buck-boost power conversion circuits.
By using a microwave transmission line, or other electrical propagating medium, electrical power may be converted. This may be used to render DC/DC-, AC/DC-, DC/AC-converters or amplifiers and radio transmitter systems.
The use of conventional DC/DC voltage converters may sometimes be problematic due to response times and cost considerations. In high frequency applications such components need to be highly optimized to function properly. There is also an increasing demand on suppliers of high frequency equipment for cost reductions at all levels, e.g. in the telecommunications industry cost reductions and efficiency optimization is a strong market driver. Furthermore, this is also true for amplifiers in high frequency applications.
Depending on circuitry configuration and applications, the above mentioned solutions may sometimes not be optimal and alternative solutions may be better suited. Furthermore, there exist many applications within high frequency applications where solutions for different types of power conversion types may find applicability.
Different types of electrical/communication configurations may require a plurality of different types of solutions within the same circuitry and in different modules interoperating with each other. The different types of solutions are not always compatible with each other and require different types of knowledge basis.
Radio frequency applications pose a complex situation in order to provide a working solution for transferring electrical signals/power to/from functions in such applications.
Another disadvantage of the prior art is that it the power conversion solutions requires a high number of semiconductors, which makes the electrical circuit large, complex and expensive.
FIG. 1a illustrates OVer Sampling (OVS) according to the prior art, which is defined as the duration of active operation state ton 101 of the switch 103 being less than the reflected wave's period time 2td in a transmission line 105. An active state is a state where the switch 103 is turned on, i.e. it goes from an inactive state to an active state. FIG. 1b illustrates SUb Sampling (SUS) according to the prior art, which is defined as the duration of active operation state ton 101 of the switch 103 being equal or greater than the reflected wave's period time 2td in the transmission line 105. Typically 100-1000 times longer. td(s) is the propagation time in transmission line 105. T(s) is the period time of current steps at transmission line 105 input, T=2td.
When using over sampling mode, two separate DC output voltages may share the same inductive and free wheel diode components by time multiplexing, thus reducing the required number of semiconductors. Over sampling mode also enables polarity change possibilities by setting one of the transmission line's ends to be shorted or open. The power conversion efficiency will be poor when using over sampling solely.
When operating in over sampling mode the voltage drop, e.g. from input DC to output DC voltage, is created in the, relative to the transmission line, mismatched output capacitor. However this type of mismatched voltage conversion (Γ≠1, Γ≠0, Γ≠−1) will not yield higher power conversion efficiency than a conventional series regulator, i.e. a Low Drop Out regulator (LDO).